They have a roadmap on their site, but release dates are never really given. I'd guess it should be out sometime this year, but version 7.3 is quite excellent already.

One of the bug things for some people with v.8 will be the ability to maintain multiple databases and be able to selectively play music from any one or combinations of them. With this ability it will be possible to keep for instance a database for classical separate from al your other music. Or your music separate from your kids' or wife's etc..

I'll finally be able to make sure that Janet Jackson never gets randomized among any of my music.